package ru.study.thinkin.chapter13;

interface Null {}

class Person {	
	
	private final String first;
	private final String last;
	private final String address;
	public static final Person NULL = new NullPerson();

	public Person(String first, String last, String address) {
	
		this.first = first;
		this.last = last;
		this.address = address;
	}

	@Override
	public String toString() {	
		return "Person "+first+","+last+","+address;
	}


	public static class NullPerson extends Person implements Null {	
	
		private NullPerson() {
			super("None","None","None");
		}
	
		@Override
		public String toString() {
			return "NullPerson";
		}	
	}	
	
}	
